Charging lead acid battery

Thread Starter

Sergio34

Joined Nov 10, 2018
51
Hello, there is something I do not understand when charging lead acid batteries (or batteries in general). Somehow chargers intrigue me... Specifically it is about my motorcycle's battery, it's a 7Ah one. When I connect a mains charger to the battery the voltage gradually rises (it takes hours) from let's say 12.6V to 13.2V. The charger is of 600mA output. However when the battery is connected to the engine and rev the engine, the voltage instantly rises to 13.2V-13.8V not gradually. What does this mean? What is the difference of charging type that motorcycle's electrical system does compare to the mains charger?
 

ElectricSpidey

Joined Dec 2, 2017
1,134
The mains charger is limiting the charge current.

The charger is trying to maintain 600mA so it raises its output voltage as the battery voltage rises.

Many chargers at some point disconnect the charge current and place a small load on the battery, and test the voltage during discharge to determine the battery charge and health.

Some of the better chargers also do desulfation cycles.
 
Last edited:

dl324

Joined Mar 30, 2015
10,709
When I connect a mains charger to the battery the voltage gradually rises (it takes hours) from let's say 12.6V to 13.2V. The charger is of 600mA output. However when the battery is connected to the engine and rev the engine, the voltage instantly rises to 13.2V-13.8V not gradually. What does this mean? What is the difference of charging type that motorcycle's electrical system does compare to the mains charger?
It sounds like the charger you're using is a trickle charger; trickle meaning a low charging current and the voltage will rise slowly. The alternator from your motorcycle is putting out more current and the maximum charging voltage is regulated by a voltage regulator.
 

Thread Starter

Sergio34

Joined Nov 10, 2018
51
Thanks, my misunderstanding I believe is not so much in theory as I have made some circuits successfully but more like in terms of how the manufacturers name the products and list the specifications. For example my mains charger's output 600mA is probably the maximum, when I connected the battery, it was partially discharged 12.4V, I guess the charger started with something like 200mA or less and not 600mA. Sorry to bother you with such a simple question, I should had measured the current of the mains charger in the beginning to understand it better and wouldn't have to post this, now it is charged already. Next time.
 

KeithWalker

Joined Jul 10, 2017
880
It works the other way around. The charger has a fixed voltage of around 13.5 volts but limits the current to the battery terminals, in your case, 600mA. As the battery is charged, it's terminal voltage increases. As it approaches the charger voltage, the current will decrease until the terminal voltage equals the charger voltage.
Regards,
Keith
 
Top